The Collaborative International Dictionary of English v.0.48:

Till \Till\, v. t. [imp. & p. p. Tilled; p. pr. & vb. n.
   Tilling.] [OE. tilen, tilien, AS. tilian, teolian, to aim,
   strive for, till; akin to OS. tilian to get, D. telen to
   propagate, G. zielen to aim, ziel an end, object, and perhaps
   also to E. tide, time, from the idea of something fixed or
   definite. Cf. Teal, Till, prep..]
   1. To plow and prepare for seed, and to sow, dress, raise
      crops from, etc., to cultivate; as, to till the earth, a
      field, a farm.
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            No field nolde [would not] tilye.     --P. Plowman.
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            the Lord God sent him forth from the garden of Eden,
            to till the ground from whence he was taken. --Gen.
                                                  iii. 23.
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   2. To prepare; to get. [Obs.] --W. Browne.
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WordNet (r) 3.0 (2006):

tilling
    n 1: cultivation of the land in order to raise crops